42
J. N. BALL AND BRIDGET I. BAKER
both ACTH and corticosterone administration in Astyanux led to transient
inhibition of the gonadotrops followed by restoration, both at the beginning and end of the course of treatment; similar but less striking changes
followed injections of saline twice daily, but not similar injections given
once daily. These observations are probably best interpreted as a stress
response, probably mediated by the ACTH-interrenal axis (see Ball and
Slicher, 1962, for evidence bearing on this interpretation).
The gonadotrops regressed in ectopic pituitary transplants in Poecilia
formosu (Olivereau and Ball, lW), in correlation with evidence of
failure of gonadotropin secretion ( Ball et ul., 1965).
5. THYROTROPS (6 CELLS OR TSH CELLS)
The thyrotrops form the second division of the pars distalis basophils
(mucoid cells) or the third division in those forms in which two gonadotrops have been demonstrated. In mammals, which display a corresponding trio of pars distalis basophils, a good deal of effort has gone into the
tinctorial differentiation of the three types. Separation of the two
gonadotrops is discussed by Herlant ( 1960, 1964), Purves ( l M ) , and
Carlon ( 1966, 1967). Separation of the TSH cells from the two gonadotrops is generally possible with a variety of staining techniques (Herlant,
1965; Purves, 1966). In teleosts, it is generally found that the TSH cells
closely resemble the gonadotrops in their staining properties, and most
attempts to separate teleostean gonadotrops and thyrotrops purely by
staining reactions have been inconclusive. However, there are exceptions.
Banington and Matty (1955) showed that in the minnow, Phoxinus, the
gonadotrops are AF - ve but the thyrotrops are AF + ve; Matty and
Matty (1959) confirmed this distinction in Rutilus, and described in other
species both A F + ve and A F - ve basophils, without functional identifications. Similarly, in Caecobarbus geertsi, the putative thyrotrops are
A F + ve, but the putative gonadotrops are A F - ve (Olivereau and
Herlant, 1954). More subtle color distinctions occur in other teleosts,
for example, in Astyanax mexicanus where both thyrotrops and gonadotrops stain with AF, but the gonadotrops stain more intensely by PAS
( Atz, 1953). In the eel, the thyrotrops are more strongly AF + ve and
AB + ve than the immature gonadotrops, and take on a slightly different
color after PAS-OG ( Olivereau and Herlant, 1960). Tinctorial distinction
between thyrotrops and gonadotrops is also possible in Poecilia, in which
the TSH cells stain a paler blue with Ox-AB at pH 0.2, and the gonadotrops, when active, contain many R granules (Section 11, B, 4 ) which are
present in small numbers, if at all, in the TSH cells. With Aliz B, the
gonadotrops stain a deep blue, but the thyrotrops take on a slatey
gray-blue.
J. N. BALL AND BRIDGET I. BAKER
both ACTH and corticosterone administration in Astyanux led to transient
inhibition of the gonadotrops followed by restoration, both at the beginning and end of the course of treatment; similar but less striking changes
followed injections of saline twice daily, but not similar injections given
once daily. These observations are probably best interpreted as a stress
response, probably mediated by the ACTH-interrenal axis (see Ball and
Slicher, 1962, for evidence bearing on this interpretation).
The gonadotrops regressed in ectopic pituitary transplants in Poecilia
formosu (Olivereau and Ball, lW), in correlation with evidence of
failure of gonadotropin secretion ( Ball et ul., 1965).
5. THYROTROPS (6 CELLS OR TSH CELLS)
The thyrotrops form the second division of the pars distalis basophils
(mucoid cells) or the third division in those forms in which two gonadotrops have been demonstrated. In mammals, which display a corresponding trio of pars distalis basophils, a good deal of effort has gone into the
tinctorial differentiation of the three types. Separation of the two
gonadotrops is discussed by Herlant ( 1960, 1964), Purves ( l M ) , and
Carlon ( 1966, 1967). Separation of the TSH cells from the two gonadotrops is generally possible with a variety of staining techniques (Herlant,
1965; Purves, 1966). In teleosts, it is generally found that the TSH cells
closely resemble the gonadotrops in their staining properties, and most
attempts to separate teleostean gonadotrops and thyrotrops purely by
staining reactions have been inconclusive. However, there are exceptions.
Banington and Matty (1955) showed that in the minnow, Phoxinus, the
gonadotrops are AF - ve but the thyrotrops are AF + ve; Matty and
Matty (1959) confirmed this distinction in Rutilus, and described in other
species both A F + ve and A F - ve basophils, without functional identifications. Similarly, in Caecobarbus geertsi, the putative thyrotrops are
A F + ve, but the putative gonadotrops are A F - ve (Olivereau and
Herlant, 1954). More subtle color distinctions occur in other teleosts,
for example, in Astyanax mexicanus where both thyrotrops and gonadotrops stain with AF, but the gonadotrops stain more intensely by PAS
( Atz, 1953). In the eel, the thyrotrops are more strongly AF + ve and
AB + ve than the immature gonadotrops, and take on a slightly different
color after PAS-OG ( Olivereau and Herlant, 1960). Tinctorial distinction
between thyrotrops and gonadotrops is also possible in Poecilia, in which
the TSH cells stain a paler blue with Ox-AB at pH 0.2, and the gonadotrops, when active, contain many R granules (Section 11, B, 4 ) which are
present in small numbers, if at all, in the TSH cells. With Aliz B, the
gonadotrops stain a deep blue, but the thyrotrops take on a slatey
gray-blue.